[ Implementing a Phase Shift block ]

GNU Radio
1

Hi Marcus,

wrote it, as I could not find it in the GRC.
block.

If you want to do coarser phase shifts (large multiples of 180deg), you
can use a delay block.

Presently I’m calculating the delay between two synchronised signals
coming
out of the USRP source (connected to a signal generator) by recording
their
samples and finding the offset between their first peak or
zero-crossing.

Now if we want to time-align them in real-time, how can we implement a
delay block that calculates the delay each time the grc flow is run and
set
the delay_value in the block accordingly so that they are time-aligned?
i.e
I don’t want to record the samples rather I’d like to know how to find
the
delay and shift any of the two signals so that they get aligned?

Best,

2

Normally, this kind of delay detection is done using cross-correlation
(or
some more applicable variant thereof such as MRC). Note also that a
delay
will give a frequency-dependent phase shift, so you may wish to use a
delay
block rather than phase shift if your signal is broadband (although I
must
admit I don’t know what the phase shift block does internally).